systemd-journalctl — Query the systemd journal
systemd-journalctl [OPTIONS...]  [MATCH] 
systemd-journalctl may be used to query the contents of the systemd(1) journal.
If called without parameter will show the full contents of the journal, starting with the oldest entry collected.
If a match argument is passed the output is
                filtered accordingly. A match is in the format
                FIELD=VALUE,
                e.g. _SYSTEMD_UNIT=httpd.service.
Output is interleaved from all accessible journal files, whether they are rotated or currently being written, and regardless whether they belong to the system itself or are accessible user journals.
All users are granted access to their private
                per-user journals. However, by default only root and
                users who are members of the adm
                group get access to the system journal and the
                journals of other users.
The following options are understood:
--help, -hPrints a short help text and exits.
--versionPrints a short version string and exits.
--no-pagerDo not pipe output into a pager.
--all, -aShow all fields in full, even if they include unprintable characters or are very long.
--follow, -fShow only most recent journal entries, and continously print new entries as they are appended to the journal.
--lines=, -nControls the number of journal lines to show, counting from the most recent ones. Takes a positive integer argument. In follow mode defaults to 10, otherwise is unset thus not limiting how many lines are shown.
--no-tailShow all stored output
                                lines, even in follow mode. Undoes the
                                effect of
                                --lines=.
--output=, -oControls the
                                formatting of the journal entries that are
                                shown. Takes one of
                                short,
                                short-monotonic,
                                verbose,
                                export,
                                json,
                                cat. short
                                is the default and generates an output
                                that is mostly identical to the
                                formatting of classic syslog log
                                files, showing one line per journal
                                entry. short-monotonic
                                is very similar but shows monotonic
                                timestamps instead of wallclock
                                timestamps. verbose
                                shows the full structered entry items
                                with all
                                fiels. export
                                serializes the journal into a binary
                                (but mostly text-based) stream
                                suitable for backups and network
                                transfer. json
                                formats entries as JSON data
                                structures. cat
                                generates a very terse output only
                                showing the actual message of each
                                journal entry with no meta data, not
                                even a timestamp.
--quiet, -qSuppresses any warning message regarding inaccessable system journals when run as normal user.
--new-id128Instead of showing journal contents generate a new 128 bit ID suitable for identifying messages. This is intended for usage by developers who need a new identifier for a new message they introduce and want to make recognizable. Will print the new ID in three different formats which can be copied into source code or similar.